I would like to close the opener/parent window when a new window is opened. However, I would also like to avoid any client-side prompts such as "Do you want to close this window?". This is the code I'm using in the newly opened window:

Nope, I'm afraid not. I think that this was introduced in JavaScript 1.3 or 1.4, but only with signed scripts, and it's not backwards compatible. And don't ask me about signed script, that's way down the "Things to Learn" list!